TITLE OF THE DATA SET Indian Ocean Radiocarbon: Data from the INDIGO 1, 2, and 3 Cruises. DATA CONTRIBUTORS H. Gote Ostlund and Charlene Grall Rosenstiel School of Marine and Atmospheric Science University of Miami Miami, Florida 33149 DOI: 10.3334/CDIAC/otg.ndp036 SOURCE AND SCOPE OF THE DATA The data file included in this subdirectory (NDP036) details C-14 activities from water samples taken at various locations and depths in the Indian Ocean. Values are presented in the internationally accepted delta C-14 convention (see, for example, Stuiver and Robinson 1974). The data were collected as part of the INDIGO 1, INDIGO 2, and INDIGO 3 cruises. The INDIGO 1 cruise collected samples in the southern Indian Ocean from February 27 through March 26, 1985. Carbon-14 measurements were made from 74 samples collected at 13 stations located between latitudes 26 degrees S and 48 degrees S. INDIGO 2 began the following year and sampled the northwestern Indian Ocean from April 1 through April 30, 1986. Carbon-14 measurements were made from 91 samples at 14 stations located between latitudes 19 degrees S and 9 degrees N. The INDIGO 3 cruise traveled south into the Southern Ocean and collected samples from January 15 through February 13, 1987. Carbon-14 measurements were made from 68 samples collected at 7 stations located between latitudes 37 degrees S and 65 degrees S. These data have been used to estimate the penetration of anthropogenic CO2 in the Indian Ocean and may be especially significant because of the inclusion of measurements from locations in the Southern Ocean near the major point of origin for the deep waters of the world's oceans. The data file also includes supporting measurements for potential temperature, salinity, density (sigma-theta), del C-13, and total CO2. DATA FORMAT Four files are provided as DOS ASCII text files in this subdirectory, including this documentation file (NDP036.TXT), a FORTRAN IV retrieval program (NDP036.FOR), a SAS input/output routine (NDP036.SAS), and a data file containing the Indian Ocean radiocarbon data (INDIGO.DAT) from the INDIGO 1, 2, and 3 cruises. Table 2 (located in the documentation that describes these data) presents a partial listing of the data file containing the Indian Ocean radiocarbon data ((INDIGO.DAT). The data file is formatted in the following way: CHARACTER STATION*3, DATE*6, CAST*3, SAMPLER*2 INTEGER BOTTOM, LAT, LONG, DEPTH, POTTEMP, SALINITY, 1 SIGTHETA, TCO2, DC13, DC14 10 READ(2,100,END=99) STATION, DATE, BOTTOM, LAT, LONG, CAST, 1 DEPTH, POTTEMP, SALINITY, SIGTHETA, 2 TCO2, DC13, DC14, SAMPLER C 100 FORMAT(1X,A3,2X,A6,2X,I4,2X,I5,2X,I4,2X,A3,2X,I4,2X,I5, 1 2X,I5,2X,I5,2X,I4,2X,I5,2X,I7,2X,A2) where STATION is the identifying number of the station (data collection site) (see Ostlund and Grall 1988); DATE is the date of sampling, presented in a six-digit format, indicating year, month, and day, respectively; BOTTOM is the depth (in meters) of the ocean bottom at the site of sampling; LAT is the latitude of the station, presented in degrees (first two digits) and minutes (last two digits), with north latitudes represented as positive; LONG is the longitude (east) of the station, presented in degrees (first two digits) and minutes (last two digits); CAST is the identifying number of the group of four Niskin sampling bottles simultaneously lowered into the water; DEPTH is the depth (in meters) at which the sample was taken; POTTEMP is the potential temperature (i.e., temperature corrected for the effect of adiabatic compression with increase in depth) given in degrees C * 1000 (see Pickard and Emery 1982); SALINITY is the fraction of dissolved salts in sea water, given in ppt(w/w) * 1000; SIGTHETA is sigma-theta, the density of seawater at the given salinity and potential temperature, given as [density (kg/m**3) - 1000] * 1000; TCO2 is the total CO2 in umol/kg; DC13 is del C-13, the deviation in per mil from standard C-13:C-12 ratio, calculated as del 13 = [(Rsa/Rst)-1] * 1000, where Rsa and Rst are the C-13:C-12 ratios of sample and standard (obtained from the National Bureau of Standards), respectively (see Stuiver and Robinson 1974); DC14 is delta C-14, the deviation in per mil of sample C-14 activity from standard C-14 activity, with correction for the effects of isotope fractionation, calculated as delta C-14 = [(Asn/Ao)-1] * 1000, where Asn is the measured C-14 activity of the sample, corrected for isotope fractionation, and Ao is the oxalic acid C-14 activity with the age corrected to 1950 A.D. and the C-13 normalized (see Stuiver and Robinson 1974; Ostlund and Grall 1988; Stuiver and Polach 1977; Broecker and Olson 1961); and SAMPLER is the identifying number of the Niskin bottle from which an individual sample was collected. Stated in tabular form, the contents include the following. _________________________________________________________________________ Variable Variable Starting Ending Variable type width column column _________________________________________________________________________ STATION Character A3 2 4 DATE Character A6 7 12 BOTTOM Numeric I4 15 18 LAT Numeric I5 21 25 LONG Numeric I4 28 31 CAST Character A3 34 36 DEPTH Numeric I4 39 42 POTTEMP Numeric I5 45 49 SALINITY Numeric I5 52 56 SIGTHETA Numeric I5 59 63 TCO2 Numeric I4 66 69 DC13 Numeric I5 72 76 DC14 Numeric I7 79 85 SAMPLER Character A2 88 89 _________________________________________________________________________ Missing values for potential temperature, salinity, and sigma- theta are represented by -9999. Missing values for total CO2 are represented by -999. REFERENCES Broecker, W. S., and E. A. Olson. 1961. Lamont radiocarbon measurements VIII. Radiocarbon 3:176-204. Ostlund, H. G., and C. Grall. 1988. INDIGO 1985-1987: Indian Ocean Radiocarbon. Tritium Laboratory Data Report No. 17. Tritium Laboratory, Rosenstiel School of Marine and Atmospheric Science, Miami, Florida. Pickard, G. L., and W. J. Emery. 1982. Descriptive Physical Oceanography: An Introduction, 4th ed. Pergamon Press, New York. Stuiver, M., and H. A. Polach. 1977. Discussion: Reporting of C-14 data. Radiocarbon 19:355-363. Stuiver, M., and S. W. Robinson. 1974. University of Washington GEOSECS North Atlantic carbon-14 results. Earth and Planetary Science Letters 23:87-90.